It is common surgical practice to use bypass grafts to help reestablish coronary artery circulation when a portion of the coronary artery is stenosed. Such a procedure is typically referred to as a coronary artery bypass graft (CABG) procedure. Typically the graft vessel used in bypassing a stenosed portion of the coronary artery is a segment of the patient's saphenous vein which is taken from the patient's leg. Other graft vessels such as the radial artery in the arm can also be used. In addition, it is common practice today for the surgeon to redirect one of the internal mammary arteries (IMA) in the chest to the stenosed portion of the left anterior descending (LAD) artery on the heart. The IMA is mobilized and then the free end is joined to the LAD, just distal to the blockage. For multiple bypass surgery, a combination of the redirection of the IMA and the grafting of vessels to the diseased coronary arteries is often used.
When a surgeon performs an anastomosis of the graft vessel to the coronary artery, it is important that the graft vessel be held steady and adjacent to the coronary artery, with a minimum of vascular trauma and a minimum of visual and surgical obstruction by instruments in the narrow operative field. The speed of performing such an anastomosis is extremely critical as well. Often the coronary artery is intentionally but temporarily occluded during the procedure, using any of a number of occlusion devices currently available, so that each anastomosis can be performed more easily. It is very important to perform the anastomosis and remove the occluding device in order to reconnect the supply of blood to the artery as soon as possible, thus minimizing trauma to the vessels and surrounding tissue.
Blood vessels are typically anastomosed end-to-end or end-to-side using any of a number of manual suturing techniques. For example, the surgeon may use a conventional needle holder in combination with a tissue grasper to suture two vessels together in the following manner. After an arteriotomy has been done on the coronary artery to create an opening to the lumen (inside) of the artery, the surgeon first passes the tip of a curved suturing needle having a suture attached to the blunt end through the graft vessel wall from the outside. Usually a knot or button is present at the trailing end of the suture to anchor the first stitch. Then the needle is passed through the coronary artery wall from inside the lumen. The needle is then passed again through the graft vessel wall from the outside. Next the surgeon grasps the needle near the tip and pulls the needle through the walls of the vessels with the suture following the path of the needle. The surgeon then pulls the suture through the vessel walls to form the first stitch. The surgeon then penetrates the tip of the needle through the inside of the coronary artery wall again, at a location spaced apart from the first stitch. The surgeon again passes the needle through the coronary artery wall and into the outside of the graft vessel wall. The surgeon grasps the needle near the tip and pulls the suture through the vessel walls to form the second stitch. This process is repeated with the surgeon carefully tensioning the suture after each stitch to draw the vessel walls together, thereby creating a running stitch around the vessel and composed of a plurality of individual suture loops. When the graft vessel wall has been thus sutured around its entire perimeter to the coronary artery wall, the two strands of suture are tied together and trimmed to complete the anastomosis. As is evident by the foregoing description, manual suturing techniques are usually tedious and time-consuming, generally requiring several minutes to complete for each anastomosis, even for a highly skilled surgeon.
In the surgical art, the use of time-tested surgical techniques is generally very important to surgeons. When suturing, a traditional technique for using a needle holder to place a curved needle into tissue is often referred to as supination, or the turning of the palm inwards. This simply means that once the tip of the curved needle is carefully placed into the tissue, the hand holding the needle holder is rotated so that the curved needle is driven through the tissue up to the point where the needle holder is clamped onto the needle. The needle holder is released from the needle, and clamped again on the portion of the needle extending from the opposite side of the tissue penetrated. Then supination is again used to pull the remainder of the needle through the tissue. Using this technique, the needle follows an arcuate path in a direction transverse to the longitudinal axis of the needle holder. It is very advantageous, therefore, that a device for facilitating the suturing of bodily tissues also allows the surgeon to use the supination technique.
There are a number of examples of devices designed to facilitate the suturing of tissue during surgical procedures. Such examples are described in U.S. Pat. No. 5,437,681 issued to Meade, et al, on Aug. 1, 1995 and U.S. Pat. No. 5,540,705, also issued to Meade, et al, on Jul. 30, 1996. Those devices drive a needle through the tissues being joined together. A disadvantage of the Meade devices, however, is the removal of the surgeon's tactile sensation as the needle is penetrated into the tissue. This may affect the surgeon's perception of control of the suturing technique. Furthermore, the Meade devices do not permit the surgeon to use hand supination when penetrating the needle into tissue. What is needed is an automated suturing device that allows the surgeon to use hand supination and to maintain tactile sensation of the needle as it is penetrating the tissue.
Several investigators have incorporated electrically powered means into suturing devices in order to automate the suturing of bodily tissues. Some of these devices are power-driven, needle-gripping tools such as described by Weintraub, et al, in U.S. Pat. No. 4,635,638 issued on Jan. 13, 1987. In U.S. Pat. No. 5,735,862 issued on Apr. 7, 1998 to Jennings, et al, a pair of electric solenoid driven gripping jaws is constructed into a pair of arms pivotally attached to each other. The jaws are automatically and alternatingly actuated to open and close when they are pivoted into proximity with each other, such that a hand-off of the needle can occur. For the Jennings device the surgeon maintains tactile sensation of the needle passing through tissue, but visibility of the tissue being sutured is not as good as with conventional manual suturing techniques. Also, because the arms are constructed to pivot with respect to each other in a plane, it would be difficult for the surgeon to use hand supination to place the needle into tissue. Other devices incorporate powered means for passing a specially designed surgical needle through tissue and have the disadvantage described earlier, that is, removal of tactile sensation and control from the surgeon. Examples of such devices are described in U.S. Pat. No. 5,545,148 to Wurster, issued on Aug. 13, 1996, and to Brunk in U.S. Pat. No. 4,899,746, issued on Feb. 13, 1990.
In the related parent patent applications, Ser. No. 08/946820 and 09/012783, shortcomings of the prior art are overcome. Embodiments of a suturing device (also referred to as a needle holder) are described which reduce the time to suture tissues. The embodiments also maintain surgeon control by permitting tactile sensation for when the needle is penetrating into tissue, and allowing the surgeon to use the hand supination suturing technique. In addition, visibility of the tissues being sutured is not obstructed by the suturing device. Despite these advantages, an opportunity to improve the device may be realized by reducing the manual force and movement necessary to actuate a trigger of the device. This would aid the surgeon in suturing especially small and delicate tissues such as blood vessels primarily because it would be easier to keep the distal end of the device steady as the needle is passed through the tissue.
The present invention is an improvement of the suturing device embodiments described in the related applications, 08/946820 and 09/012783, in that the advantageous features are retained in a novel combination with an electrically powered means, thus replacing the trigger with a small control button. This enables the surgeon to suture especially delicate bodily tissues easily and quickly with a single instrument. It is especially useful for creating a vascular anastomosis such as for a CABG procedure.